Swift - How to do a custom slide animation?

I've been looking for swift code to make simple custom slide transitions between views (just left to right or right to left, without bounce) but I only found code for complicated animations. Thanks everyone for your help !

private var presenting = true
// MARK: UIViewControllerAnimatedTransitioning protocol methods
// animate a change from one viewcontroller to another
func animateTransition(transitionContext: UIViewControllerContextTransitioning) {
// get reference to our fromView, toView and the container view that we should perform the transition in
let container = transitionContext.containerView()
let fromView = transitionContext.viewForKey(UITransitionContextFromViewKey)!
let toView = transitionContext.viewForKey(UITransitionContextToViewKey)!
// set up from 2D transforms that we'll use in the animation
let offScreenRight = CGAffineTransformMakeTranslation(container.frame.width, 0)
let offScreenLeft = CGAffineTransformMakeTranslation(-container.frame.width, 0)
// prepare the toView for the animation
toView.transform = self.presenting ? offScreenRight : offScreenLeft
// set the anchor point so that rotations happen from the top-left corner
toView.layer.anchorPoint = CGPoint(x:0, y:0)
fromView.layer.anchorPoint = CGPoint(x:0, y:0)
// updating the anchor point also moves the position to we have to move the center position to the top-left to compensate
toView.layer.position = CGPoint(x:0, y:0)
fromView.layer.position = CGPoint(x:0, y:0)
// add the both views to our view controller
container.addSubview(toView)
container.addSubview(fromView)
// get the duration of the animation
// DON'T just type '0.5s' -- the reason why won't make sense until the next post
// but for now it's important to just follow this approach
let duration = self.transitionDuration(transitionContext)
// perform the animation!
// for this example, just slid both fromView and toView to the left at the same time
// meaning fromView is pushed off the screen and toView slides into view
// we also use the block animation usingSpringWithDamping for a little bounce
UIView.animateWithDuration(duration, delay: 0.0, usingSpringWithDamping: 1, initialSpringVelocity: 1, options: nil, animations: {
// slide fromView off either the left or right edge of the screen
// depending if we're presenting or dismissing this view
fromView.transform = self.presenting ? offScreenLeft : offScreenRight
toView.transform = CGAffineTransformIdentity
}, completion: { finished in
// tell our transitionContext object that we've finished animating
transitionContext.completeTransition(true)
})
}
// return how many seconds the transiton animation will take
func transitionDuration(transitionContext: UIViewControllerContextTransitioning) -> NSTimeInterval {
return 0.4
}
// MARK: UIViewControllerTransitioningDelegate protocol methods
// return the animataor when presenting a viewcontroller
// remmeber that an animator (or animation controller) is any object that aheres to the UIViewControllerAnimatedTransitioning protocol
func animationControllerForPresentedController(presented: UIViewController, presentingController presenting: UIViewController, sourceController source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
// these methods are the perfect place to set our `presenting` flag to either true or false - voila!
self.presenting = true
return self
}
// return the animator used when dismissing from a viewcontroller
func animationControllerForDismissedController(dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
self.presenting = false
return self
}
}